From 6eeff1960cb18957a177f8a9447b444c05dac2bd Mon Sep 17 00:00:00 2001
From: Rich-Harris <richard.a.harris@gmail.com>
Date: Mon, 21 Nov 2016 16:36:55 -0500
Subject: [PATCH] add on and fire methods

---
 compiler/generate/index.js                | 24 ++++++++++++++++++++++-
 test/compiler/events-lifecycle/_config.js | 15 ++++++++++++++
 test/compiler/events-lifecycle/main.html  |  1 +
 3 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 test/compiler/events-lifecycle/_config.js
 create mode 100644 test/compiler/events-lifecycle/main.html

diff --git a/compiler/generate/index.js b/compiler/generate/index.js
index ec7670c497..57cc64bbec 100644
--- a/compiler/generate/index.js
+++ b/compiler/generate/index.js
@@ -220,6 +220,8 @@ export default function generate ( parsed, template, options = {} ) {
 				deferred: Object.create( null )
 			};
 
+			var callbacks = Object.create( null );
+
 			function dispatchObservers ( group, newState, oldState ) {
 				for ( const key in group ) {
 					if ( !( key in newState ) ) continue;
@@ -238,6 +240,15 @@ export default function generate ( parsed, template, options = {} ) {
 				}
 			}
 
+			this.fire = function fire ( eventName, data ) {
+				var handlers = eventName in callbacks && callbacks[ eventName ].slice();
+				if ( !handlers ) return;
+
+				for ( var i = 0; i < handlers.length; i += 1 ) {
+					handlers[i].call( this, data );
+				}
+			};
+
 			this.get = function get ( key ) {
 				return state[ key ];
 			};
@@ -260,13 +271,24 @@ export default function generate ( parsed, template, options = {} ) {
 				};
 			};
 
+			this.on = function on ( eventName, handler ) {
+				callbacks[ eventName ] || ( callbacks[ eventName ] = [] ).push( handler );
+
+				return {
+					cancel: function () {
+						const index = callbacks.indexOf( handler );
+						if ( ~index ) callbacks.splice( index, 1 );
+					}
+				};
+			};
+
 			this.teardown = function teardown () {
 				mainFragment.teardown();
 				mainFragment = null;
 
 				state = {};
 
-				${templateProperties.onteardown ? `template.onteardown.call( this );` : ``}
+				this.fire( 'teardown' );${templateProperties.onteardown ? `\ntemplate.onteardown.call( this );` : ``}
 			};
 
 			let mainFragment = renderMainFragment( this, options.target );
diff --git a/test/compiler/events-lifecycle/_config.js b/test/compiler/events-lifecycle/_config.js
new file mode 100644
index 0000000000..24b9a03529
--- /dev/null
+++ b/test/compiler/events-lifecycle/_config.js
@@ -0,0 +1,15 @@
+import * as assert from 'assert';
+
+export default {
+	test ( component ) {
+		let count = 0;
+
+		component.on( 'teardown', function () {
+			assert.equal( this, component );
+			count += 1;
+		});
+
+		component.teardown();
+		assert.equal( count, 1 );
+	}
+};
diff --git a/test/compiler/events-lifecycle/main.html b/test/compiler/events-lifecycle/main.html
new file mode 100644
index 0000000000..7c89b545c5
--- /dev/null
+++ b/test/compiler/events-lifecycle/main.html
@@ -0,0 +1 @@
+<div></div>